WO2012095081A1

WO2012095081A1 - Lighting means and method for operating same

Info

Publication number: WO2012095081A1
Application number: PCT/DE2011/002167
Authority: WO
Inventors: Christoph Kaiser
Original assignee: Karlsruher Institut für Technologie
Priority date: 2010-12-27
Filing date: 2011-12-22
Publication date: 2012-07-19
Also published as: EP2659503B9; RU2013135113A; EP2659503A1; US9589784B2; EP2659503B1; RU2604643C2; CA2822881A1; US20160172181A1

Abstract

The invention relates to a lighting means having a gas volume and a coaxial HF-energy injection device for exciting same with surface waves. According to the invention, the coaxial HF-energy injection device (3) comprises a central conductor (4) guided through the gas volume (2).

Description

Title: Lechtrtlittel and operating procedures for it

description

The present invention relates to the generic term Bean ^¬ claimed and thus relates to bulbs. In the present case, light sources are sources of visible, ultraviolet or infrared optical radiation which are operated with electrical energy. In principle, it is desirable to illuminate illuminants with a reasonable expenditure of energy very brightly. It has already been proposed to excite a gas volume by supplying electrical high-frequency energy so far that a luminous plasma is formed.

A device for plasma excitation with microwaves is known from DE 103 35 523 B4, in which a microwave conductor feed line is branched and there are formed stalk electrodes whose length leads to a microwave phase shift.

A plasma generating device using microwaves is further known, for example, from US 4,908,492. There is proposed a cylindrical RF conductor arrangement with a cylindrical outer conductor and a helical inner conductor, between which microwave energy is supplied. Within the helical coil is a discharge tube to be ordered. Restrictions on dimensions and shape should be eliminated and sufficient energy should be able to be coupled into the gas or plasma. It should be mentioned as a light source of high brightness and short wavelength for purposes of optical reactions.

US 5,072,157 discloses a discharge tube assembly with an excitation device and with a discharge tube formed of transparent dielectric material. The excitation device is designed to excite surface waves in the filling of the discharge tube. In this case, at least one impedance matching network is provided between a coupling-in point and a high-frequency power source.

From US 4,049,940, which is considered to be the closest prior art, a device is known in which a plasma is generated in a gas column by exciting a surface wave with high-frequency energy. The surface wave generating means for RF energy injection extends only over part of the gas column and so much power is provided in the exciting electric field that the generated plasma expands beyond the corresponding part of the gas column. In one embodiment, the gas column is comprised in an elongate, insulated housing, wherein a first metallic tube, which is open on both sides, and a second tube, which surrounds the first, so that a coaxial arrangement is obtained, are provided. Although the microwave excitation of the gas volumes in light ^¬ convey to the prior art per se beneficial and he wishes ^¬ because for example, high luminance can be achieved. The disadvantage, however, is that as a rule the use of resonant structures is required, which is contrary to the operation with cheaper broadband ^{energy sources ¬} ; In addition, shading of the luminous volume by the surrounding structures is often caused or shielding of the coupled-in high-frequency energy is required.

It is desirable to provide at least some of the mentioned problems with at least partial relief. This object is bean sprucht ^¬ in independent form. Preferred embodiments can be found in the Un ^¬ dependent claims.

Thus, the present invention proposes in a first

The idea is to have a light source with a gas volume and a coaxial RF energy input device for exciting it with evanescent fields of surface waves, wherein it is provided that the coaxial RF energy input device has a central conductor guided into the gas volume.

Because a central conductor, that is to say a central conductor arranged on the axis of the coaxial RF energy coupling device, is used, the light generated by plasma lamps is initially not shaded by the latter. It should be noted that although the central conductor is preferably located exactly centrally on the axis of the coaxial RF energy coupling device, deviations, preferably only small deviations from a central position, are possible. This reduces the cost of the lamp insofar as possibly lower manufacturing precision is required. However, it is relevant that the gas volume surrounds the central conductor; Thus, the light emerging from the plasma chamber is not shadowed by the coupling structure.

The arrangement according to the invention generates surface waves particularly efficiently, which is advantageous since surface waves have at most a low electromagnetic radiation. Accordingly, shielding is not required or at best only very small shielding measures have to be taken. This is advantageous insofar as the shielding has typically led to a significant reduction in the efficiency, that is to say the efficiency, of the lamps or lamps operated by microwaves.

It is possible and preferred to design the gas volume as high pressure volume to serve lighting purposes. This is especially true if a light source with high brilliance, that is high color temperature and high luminance, is desired. It should be mentioned here, for example, the lighting in the interior, which can be achieved by suitable gas fillings, etc. possibly even a desired color temperature. The pressure inside high pressure lamps can be a few bar. The fact that the present invention can also be used for low-pressure lamps operating at pressures in the range of up to a few millibars is also mentioned. Here too, resulting UV radiation can either be emitted and used directly as such or converted via fluorescence substances into spectral regions which are more suitable for the respective illumination and / or irradiation purposes.

Alternatively, it is possible to choose an average pressure for the gas volume, which is advantageous if the light source is to generate short-wave optical radiation, that is to say ultraviolet radiation, which is to be used directly, or via conventional fluorescence means visible radiation is to be implemented. In this way, for example, bulbs can be provided for generating biologically active radiation, for example for water disinfection in sewage treatment plants or for the food industry, as well as illuminants with which photochemical reactions are triggered in paint shops or the like, that is, for example, hardening of coatings. Adhesives and the like is initiated.

It should be noted that in the luminous means of the present invention, in particular, their enveloping bodies, which typically consist of suitable types of glass, may be coated with fluorescent dyes and the like. may be provided to provide in per se known manner for the conversion of the UV radiation generated in the light source in the desired spectral ranges.

It should be pointed out that, depending on the desired pressure range and intended use, the light source is adjusted accordingly. will be fitting. Thus, pressure-dependent different thicknesses may be optionally for surrounding the gas volume Col ^¬ ben selected and / or different materials, for example in the case of UV medium pressure lamps materials that are particularly well UV-transparent, for example quartz glass. It should be noted that the gas volume will be typically elongated, that is arranged approximately in an elongated cylinder or the like.

The coaxial line is typically designed for the energy supply or the power line in the fundamental mode of the coaxial conductor. In that regard, the illuminant of the present invention is a non-resonant system, which in turn makes it possible to operate the illuminant broadband, that is, for example, to use a broadband Hochfre ^¬ quenz energy source or even pulsed, even briefly pulsed energy to feed. There is a significant advantage over cavity resonator structures, since there due to the Resonatoreigenschaft a broadbandxges pulses is not possible; so that there short, that is particularly broadband impulses, not be generated. Moreover, by enabling a non-resonant excitation, a demand for the precision of the high-frequency energy source that has been reduced to that extent can also be achieved, which in turn reduces the costs.

Another advantage resulting from the possibility of non-resonant operation is that no particular dimensions must be observed for the components used to satisfy any resonance conditions. This allows in particular the use of very small Structures and thus creates a high potential of miniaturization. In addition, even if, for example, the frequency of the high-frequency energy source varies slightly due to thermal effects or the like, there is no significant variation in the luminosity, since the coupling of the electromagnetic wave into the plasma takes place virtually independently of the frequency.

The arrangement will typically be designed so that power that is not needed for plasma generation is reflected back. It should be noted that the possible power consumption of the light source varies after the start, for example because the lamp must still be warm and thereby energy absorbing processes are improved, such as the pressure increases due to the heating or the like. For high-pressure lamps, the pressure can rise to a few hundred bars. The self-regulation through power reflection is advantageous in that no power regulator must be connected upstream.

The energy transport into the plasma takes place by evanescent fields of the surface wave, so that a galvanic coupling is not absolutely necessary. It is particularly advantageous in the inventive arrangement so that the microwaves have only a small distance from the central conductor in a significant amount of power, which reduces the required shielding. Therefore, the central conductor can be galvanically connected to the gas volume, but this is not mandatory. Rather, it is preferred if the central conductor is not galvanically connected to the gas volume, but is galvanically separated from it. This offers advantages, because the central conductor with galvanic separation of the gas volume also not can come into contact with the plasma. Accordingly, the center conductor can not be attacked by the plasma, as otherwise electrodes, which improves the durability. In a particularly preferred variant, the central conductor protrudes beyond the coaxial jacket. In this case, the central conductor is still preferably within the gas volume in the region projecting beyond the coaxial jacket. The central conductor is thus included in the gas volume.

The gas light space can be at least largely, preferably completely shielding-free. Plasma excitation and surface wave formation can take place in the actual coupling structure, wherein the surface wave formed can extend along the central conductor along the central conductor along the shielding of the coupling structure and at least through the protruding coaxial sheath over the coaxial sheath initially surrounding it in that area, in which the central conductor protrudes beyond the jacket, a complete shielding freedom is given. Since no high-frequency waves must be shielded, light is not shaded there either.

Protection is also claimed for a method of operating a luminous means in which radiofrequency energy is coupled into a gas volume via a coaxial central conductor, in particular in an arrangement as described in US Pat. No. 4,049,940, however, there without the coaxial central conductor according to the invention.

It is particularly preferred when high-frequency energy is coupled in broadband or pulsed. The invention will now be described by way of example only with reference to the drawings. In this is shown in Fig. 1, a coupling structure for a light source

of the present invention.

Of FIG. 1 1 comprises a generally designated 1 light ^¬ medium a gas volume 2 and a coaxial RF energy coupling device 3 for exciting the gas volume 2 using surface acoustic waves, wherein the coaxial RF energy launcher 3 a into the gas volume 2 guided center ^¬ conductor 4 has. In the present case, the luminous means 1 is filled as a low-pressure luminous means with a gas of in this case 30 mbar, here for example argon. The gas volume 2 is enclosed in an elongated glass bulb 2 a, which is indicated only by dashed lines in Fig. 1. The glass bulb does not extend into the interior of the coupling structure 3, but only close to it. Thus, a short circuit of the microwave energy to be coupled to the inner conductor is avoided by the plasma. In this glass cylinder 2 a is, galvanically separated from the further coupling structure 3, the central conductor. 4

The coupling structure 3 is in the present case, apart from the central conductor 4, formed as described in US 4,049,940 per se. Provided here is also a coaxial energy supply line 3a, which is connected in the interior of a coupling space 3b with a capacitive coupling plate 3c, which in some areas closely approaches a coaxial jacket 3d. The coaxial sheath 3d has an axis on which the central conductor 4 runs and thus forms with the central conductor a coaxial RF energy coupling device. The coupling structure 3 further has a coupling slot 5 for impressing the surface wave and a front plate 6. As the comparison with US 4,049,940 shows, the present arrangement thus differs in particular by the additional central conductor 4 of the prior art. Incidentally, this protective right is incorporated in full for the purpose of disclosure. The arrangement is operated as follows:

Via the coaxial feed line 1, energy is conducted via the coaxial feed line and the capacitive coupling to the gas volume 2 from an HF energy source (not shown), which may be formed in the remaining part of the light source or separately. The capacitive coupling couples energy into the coaxial structure of coaxial sheath 3d and center conductor 4 for energy transfer in a coaxial fundamental mode. The supplied energy forms a surface wave along the central conductor which extends along the central conductor beyond the coupling structure and thus also extends into the region of the oblong glass bulb outside the actual coupling structure, ie beyond the front plate 6, and the gas volume becomes placed in the plasma state.

The coupling takes place without resonance conditions having to be maintained so that pulsed operation is readily possible. Measurements have shown that no significant microwave power is emitted. While the use of a glass bulb has been described above, this is not mandatory. In particular, but not exclusively, the use of suitable ceramics is also suitable for high-pressure lamps. Also, the use of an electrically non-separated inner conductor for high-pressure lamps with ceramic insulators is more suitable.

In summary, therefore, a luminous means and a method for operating a luminous means have been described in which high-frequency waves are coupled into a gas volume for generating and maintaining plasma with only little shading, a small construction is achieved, ensuring broadband transmissivity for high-frequency waves in the component. tet, self-consumption or Leerlaufver ^¬ consumption is very low and the high-frequency wave can be easily transported into the interior of the bulb.

Claims

claims

1. Lamp (1) with a gas volume (2) and a coaxial RF energy ~ coupling device (3) for the excitation of the same with surface waves, characterized in that the coaxial RF energy Einkopplungs- device (3) into the gas volume ( 2) guided central conductor (4).

2. Lamp according to the preceding claim,

characterized in that

the Gasvoluraen is a high-pressure gas volume and is ^¬ preferably designed for lighting with high brilliance;

the volume of gas is a low pressure gas volume and the illuminant is designed for UV generation and / or lighting purposes;

or

the gas volume is a medium-pressure gas volume, and the illuminant and / or the generation of biologically and / or chemically active radiation, in particular for water disinfection with UV radiation, is preferably designed.

3. Lamp according to one of the preceding claims, characterized in that the coaxial line for energy gieeinspeisung and / or conduction in the basic mode is laid out.

4. Lamp according to one of the preceding claims, characterized in that it is designed to excite the gas volume with non-resonant energy.

5. Lamp according to one of the preceding claims, characterized in that the RF energy Einkopplungs- device for coupling pulsed energy and / or broadband RF energy is formed and / or a pulsed or broadband RF energy source comprises ^' st.

6. Lamp according to one of the preceding claims, characterized in that it is designed for self-regulation by power reflection.

7. Lamp according to one of the preceding claims, characterized in that the central conductor is electrically isolated from the gas volume.

8. Lamp according to one of the preceding claims, character- ized in that the central conductor extends at a distance from the coupling point on the coaxial jacket.

9. Lamp according to one of the preceding claims, character- ized in that the gas light space is at least largely, preferably completely shielding.

10. A method of operating a luminous means, in which a gas volume is brought to surface with surface waves of exciting, coaxially supplied RF energy, characterized in that the RF energy is transmitted via a co axial central conductor is coupled into the gas volume.

11. The method according to the preceding claim, characterized in that the RF energy is coupled broadband and / or pulsed and / or that the light-emitting means by power reflection self-regulates.